Conclusion

Files turn small snippets into small programs.

You learned how to read text, write text, build paths, use with for file cleanup, import modules, protect script entry points with a main block, and organize a small project layout.

The central pattern is:

read input -> compute -> write output

In code:

That script shape will return later when experiments read data, compute arrays, save plots, and write result summaries.

What comes next

The next chapter introduces small objects, records, and type hints.

Files and modules create a need for clearer data shapes. Once a program passes records between functions, it helps to name those records and document what each function expects.